Taking your points in reverse, yep, the new Candle Dyke was indeed Kendal Dyke when Dick quanted his way into it. I don't know how or when the named got changed, but I assume the new name is a lazy corruption of the old one.

Regarding Malthouse/Ranworth, one of the footnotes (down near the scale) says that this was the way Ransome named them (actually incorrectly, as you say). Because the maps are based on his two Broads books I've hung on to the names the way he used them.

I think Malthouse Broad is actually often known as Ranworth Broad because it contains Ranworth Staithe and the few houses that comprise Ranworth -- which of course weren't on the 'other' Broad because it was private (as it still is, indeed.) But note that the pub that's there was the Malsters Arms (now just the Malsters), not the Ranworth Arms or whatever.

When I was there last year I made a point of asking the people at the observation place on the (real) Ranworth Broad about this, and they told me that very many people confused the two.

But your comments are very valuable, and many thanks for them, because they show you gave critical thought to it and that was exactly what I wanted.